Contraindications to use
Hypersensitivity to letrozole; endocrine status, characteristic for premenopausal period; pregnancy, breastfeeding period; children under 18 years of age.
severe hepatic insufficiency (Child-Pugh class C), severe renal insufficiency (CK<10 ml/min), concomitant use with potent inhibitors of CYP3A4 and CYP2A6 isoenzymes. Concomitant use with drugs with a narrow therapeutic index, excretion of which depends mainly on CYP2C19 isoenzyme.
Use in pregnancy and lactation
Use is contraindicated in pregnancy and during breastfeeding.
Use in hepatic dysfunction
Caution should be exercised in patients with severe hepatic insufficiency (Child-Pugh class C).
Use in renal dysfunction
Caution should be exercised in patients with severe renal impairment (creatinine clearance < 10 ml/min). The ratio between the expected therapeutic effect and possible risks of treatment should be carefully weighed.